Lifting-jack



sTATEs PATENT Brion.

ROBERT W. DAVIS AND DANIEL DAVIS, OF YELLO\V SPRINGS, OHIO.

LIFTINGr-J'ACK.

Specification of Letters Patent No. 17,027, dated April 14, 1857.

To all fui/wm t may concern:

Be it known that we, ROBERT W. Davis and DANIEL DAvis, of YellowSprings, in the county of Green and State of Ohio, have invented a newand Improved Lever-J ack;

p and we do hereby declare that the following is a full and eXactdescription thereof, reference being had to the accompanying drawings,making partrof this specification and representing a central verticalsection of our improved lever-j ack.

We prepare a suitable standard A, generally made of cast iron; in whichthe other parts are mounted. In the middle of this standard slides thetraveling ratchbar B, which isA kept in place by the portions 7L, z',&c., of the standard, which surround it, and by a guide b, at thebottom, sliding in suitable grooves. On one side of this bar are notchesg, of any required degree of fineness. Near the top of the standard is astationary pawl f, which serves to retain the ratch-bar at any height towhich it is raised, its posi- [tion being opposite to the solid portioni, of

the standard, and consequently holding the ratch-bar principally bypressing it against said solid portion 'of the standard. Below theretaining pawl is situated a grip D, which embraces the ratch-bar andreciprocates, up and down thereon, in the manner presently to bedescribed. The back of the aperture of the grip is plane, and comes inimmediate contact with the plane back of the ratch-bar; and in the frontpart of the grip is situated a pawl d, which takes into the notches g,of the ratch-bar, substantially as represented. The grip rests uponupright connecting rods, G, there being one on each side of theratchbar. The grip, or the connecting rods, may have suitable notches ordepressions, to receive corresponding projections on the opposite rodsor grip, and thus keep the rods in place, as shown at a; and to keep therods more surely in place, guide pins n, a, may be used; thus allowing aperfertly free motion of the connecting rods. The lower ends of theseconnecting rods are pivoted at Z, to the lever 0, to which the power isapplied, as far from the fulcrum m, of the lever as may be desired. Thepositions of the fulcrum and pivot are such as to keep the connectingrods as nearly in a vertical position as possible, although, when theyare of considerable length as represented, the variation from a verticalposition can be only slight, so that the power applied acts alwaysalmost precisely in the direction in which t-he ratch-bar moves. Thelever and connecting rods should also be arranged so that when the leveris brought down to its lowest position, the pivot Z, will be nearly oreXactly in a straight line between the fulcrum m, and the centralbearing point of the connecting rods against the reciprocating grip l),as represented by dotted lines in the drawing.

` The action of this lever jack is obvious When the lever C, is raised,as shown in the drawing, the reciprocating grip D, slides down on theratch-bar, and its pawl CZ, takes into a lower notch of the ratch g.Then, when the lever is pressed down to the hori- Zontal position, asshown by dotted lines, the reciprocating grip is raised, andconsequently lifts the ratch-bar with it. The stationary pawl f, thenretains the ratch-bar at the height to which it is moved, when the leveris raised again for a new hold. lVhen comparatively light articles areto be raised, the lever may be lifted as far as it will go, and thuswill lift the ratch-bar two or more notches, whereby the jack worksexpeditiously; but when very heavy weights are to be raised, the levermay be lifted (say to an angle of 45 degrees with the horizon,) onlysuciently to raise the ratch-bar a single notch, whereby a slower actionbut greater power may be produced. To let down the ratchbar, both thepawls ci, and f, are drawn out lof the ratch, and it then descends byits own weight. And if it is desired to let a weight down slowly, whenthe lever is in a horizontal position, withdraw the stationary pawl;then raise the lever; then allow the stationary pawl to engage with theratch, and lift the grip pawl; then lower the lever. By repeating thisoperation, any weight, however heavy, may be let down as gradually as itis raised.

The advantages of the reciprocating grip, arranged and operating asdescribed, are, principally, that it holds the ratchbar rmly without anyside pressure thereof, and consequently produces no side strain on saidratch-bar, the whole clutching power being within itself, leaving saidratch-bar perfectly free in its motions; and that the pawl CZ, situatedtherein, holds principally by pressing it against the back of theratchbar, and not by the strength of the teeth of the ratch. This, also,`in connection with the connecting rods, as described, enables the forceto be applied almost precisely in thedirection of the ratch-bars motion,thus securing the full force of the power', and causing littleresistance by friction, as well as producing little or no strain on theparts.

We do not claim the ratch-bar, grip,

Y pawls, or connecting rods herein described;

but

What we claim as our invention and de- 10 sire to secure by LettersPatent, is-

The application of the power centrally beneath the self-clutching grip,or collar, whereby its action is directed in the line of the axis of theratchet-bar, for the purpose specified.

R. W. DAVIS. DANIEL DAVIS. Witnesses:

A. W. SROUFE, A. S. DAVIS.

